Sagan, writing from beyond the grave (actually his new book, The Varieties of Scientific Experience, is an edited version of his 1985 Gifford Lectures), asks why, if God created the universe, he left the evidence so scant. He might have embedded Maxwell’s equations in Egyptian hieroglyphs. The Ten Commandments might have been engraved on the moon. "Or why not a hundred- kilometer crucifix in Earth orbit?… Why should God be so clear in the Bible and so obscure in the world?" He laments what he calls a "retreat from Copernicus," a loss of nerve, an emotional regression to the idea that humanity must occupy center stage. Both Gingerich and Collins, along with most every reconciler of science and religion, invoke the anthropic principle: that the values of certain physical constants such as the charge of the electron appear to be "fine-tuned" to produce a universe hospitable to the rise of conscious, worshipful life. But the universe is not all that hospitable-try leaving Earth without a space suit. Life took billions of years to take root on this planet, and it is an open question whether it made it anywhere else. To us carboniferous creatures, the dials may seem miraculously tweaked, but different physical laws might have led to universes harboring equally awe-filled forms of energy, cooking up anthropic arguments of their own.

George Johnson is author of Fire in the Mind: Science, Faith, and the Search for Order and six other books. He resides on the Web at talaya.net